# Find magnitude of acceleration on a Ca ion, given electric field.

1. Feb 3, 2013

### monnapomona

1. The problem statement, all variables and given/known data

The electric field strength across a typical cell membrane is about 107 N/C. Given this information, find the magnitude of the acceleration of a single charged Ca+1 ion as it penetrated throught the cell wall. Ignore any resistive forces.
One atomic mass unit is 1.66 x 10-27 kg.

2. Relevant equations
F = ma
F=q0E

3. The attempt at a solution

I was thinking of multiplying the charge with how many protons a Ca ion has so:

F=q0E
= (20$\bullet$1.6*10-19C)(107 N/C)
= 3.2*10-11 N

Then I manipulated for acceleration in F=ma and got 1.93*1016 m/s?

Is this the correct method for finding the magnitude of acceleration?

2. Feb 3, 2013

### cepheid

Staff Emeritus
Ca1+ means that the charge on the ion is only unbalanced by ONE proton charge. I.e. the atom has lost one electron, leaving it with a net positive charge due to ONE extra proton whose charge is unbalanced.

3. Feb 3, 2013

### monnapomona

So would it be correct if I just use q=+1.6*10-19 C in the formula to find force?

Last edited: Feb 3, 2013
4. Feb 3, 2013

### cepheid

Staff Emeritus
Yes.

5. Feb 3, 2013

### monnapomona

Okay so I used q=+1.6*10-19 C in the formula and got F = 1.6*10-12 N. To find the magnitude of acceleration, I manipulated for a in F = ma and got 9.64 * 1014 m/s as the answer but I inputted it in my online homework assignment and apparently it's wrong.

Should I use a different formula to find acceleration?

Edit: I used 1.66*10-27 kg as the mass.

6. Feb 3, 2013

### haruspex

That's one atomic mass unit. How many of those per calcium atom?

7. Feb 3, 2013

### monnapomona

To get atomic mass, do I need to add protons and neutrons in Calcium together? So 40?

8. Feb 3, 2013

### cepheid

Staff Emeritus